The use of wood-base panels in humid environments, in general, presents low durability due to contact with water. In order to increase durability and reduce the attack of fungi, studies had been developed using resin with zinc oxide (ZnO) nanoparticles. This work aimed to produce medium density fiberboard with urea-formaldehyde resin and melamine-formaldehyde adding 0.5% and 1.0% of ZnO nanoparticles for the physical properties evaluation. All treatments were classified as medium density according to ABNT NBR 15.316-2 (2015) with values ranging between 550 and 800 kg*m-³. No differences were found between the two commercial adhesives used. The addition of 1.0% of nanoparticles resulted in lower density panels, higher moisture contents, and, after immersion in water for 24 hours, higher values of swelling in thickness. These results are explained by the lower compaction of the boards due to rapid cure of the adhesive using higher percentages of ZnO nanoparticles. The best treatment of the panels was with melamine-formaldehyde resin and 0.5% of nanoparticles.

The Brazilian Code ABNT NBR 7190 (1997) is currently under review process and one of the proposals is the change and add of some test procedures. Several specimen geometric configurations and test conditions have been evaluated by the study committee CE-02:126.10. The aim of this paper was the analysis of the tensile strength perpendicular to the grain through the current Brazilian Code and from an adaptation of ISO 13910 (2005). Pine and Indian Cedar were used and simplified relationships were proposed. Numerical simulations were performed to identify the stress distributions in the specimens. The results obtained by ISO 13910 (2005) did not differ statistically for the two species. Brazilian standard method cedar had a higher strength value than pine. The simplified ratios obtained ranged between 0,017 and 0,123. The numerical simulations of ISO 13910 (2005) specimens showed predominant failure by tension in the lower fiber due to stress concentration.

Oriented strand board (OSB) panels, like plywood, are destined for structural use. Both of them may undergo preservative treatments that extend their lifetime and increase their resistance against weathering and xylophagous agents. One possibility is a heat treatment where the wood is exposed to temperatures above 130°C (403 K), which causes chemical, physical, and mechanical changes. The aim of this work was to produce OSB made of Pinus taeda thermally treated without replacement of atmosphere for an inert gas. The physical properties of density, moisture content, and thickness swelling in water immersion for 24 hour were evaluated. The mechanical properties of static bending were determined by the modulus of elasticity (MOE), modulus of rupture (MOR), and an internal bond test. Boards were heattreated at 160, 180, and 200°C (433, 453 and 473 K), and panels were produced with heat-treated strands at 160 and 180°C (433 and 453 K). The heat treatment of boards did not affect mechanical properties compared to the control treatment. The thermal treatment of strands reduced the physical and mechanical performances of the panels.

Oriented Structural Straw Board (OSSB) panels are composites made from straw originally from agricultural residues and non-formaldehyde based adhesive, whose main application is for construction as a closing and ceiling material. The objective of this study was to evaluate the effect of the polyurethane adhesive content on physical and mechanical properties of OSSB produced with locally available SbS (soybean straw). Four castor oil based polyurethane ratios (6%, 9%, 12% and 15%, by mass of the SbS) were tested. OSSB was evaluated according to European standards for wood-based composites; also, a physical and chemical characterization of the SbS was performed. SbS has an irregular shape, which reduced the OSSB mechanical performance due to the low densification of the composite and the development of transversal cracks on the SbS after the OSSB manufacturing process. The static bending and thickness swelling performance of SbS OSSB was not improved by the increase of polyurethane adhesive content. SbS low ash content and neutral pH extractives indicates that probably its chemical properties should not affect the setting of the adhesive.

No abstract

Oriented Strand Board is a structural wood composite with applications that require good physical and mechanical performance. The addition of ZnO nanoparticles is an alternative that has been studied in order to improve the properties of Oriented Strand Board panels. However, there is no information about its effect Oriented Strand Board. The aim of this work was to evaluate the influence of the addition of zinc oxide nanoparticles in two different percentages (0,25 % and 0,50 %) on the physical-mechanical properties of Oriented Strand Board panels produced with phenol-formaldehyde resin and on the heat transfer during hot-pressing. Oriented Strand Board panels were produced and tested according to European Standards. The addition of ZnO nanoparticles improved the dimensional stability of the panel, reducing its thickness swelling, and also increased the screw withdraw strength. The heat transfer during hot-pressing increased the temperature more quickly on boards with nanoparticles addition; on the other hand the final temperature of the control treatment was higher.

No abstract

<p>Atualmente, devido ao enorme apelo ambiental, estão sendo usados produtos mais sustentáveis e renováveis, um exemplo disso são os compósitos cimento-madeira. Estes compósitos são utilizados na construção civil como isolantes termo acústicos e em usos não estruturais, como forros e revestimento de parede, porém a incidência de defeitos pode limitar sua utilização, principalmente quando produzido em nível laboratorial. Devido a isto, o objetivo do presente trabalho foi aplicar e analisar ferramentas da qualidade no processo produtivo de compósitos cimentícios com madeira de <em>Eucalyptus grandis</em>. Os corpos de prova foram produzidos conforme a norma ABNT NBR 7215 (2019) seguindo o traço de 1: 0,1 : 0,6 de cimento, madeira e água, respectivamente. Foram realizados os ensaios de densidade, módulo de elasticidade e resistência à compressão aos 7 dias e a análise foi realizada por meio do software MiniTab, as ferramentas utilizadas foram diagrama de Pareto, diagrama de Ishikawa, gráfico por variáveis e capacidade de processo. Foi possível analisar que os principais defeitos foram a incidência de pequenos poros, rompimento por esmagamento e resistência à compressão aos 7 dias inferior a 5 MPa. Os compósitos podem ser utilizados como blocos de vedação em sistemas construtivos leves e o processo produtivo se mostrou aceitável, embora melhorias possam ser realizadas no processo produtivo a fim de corrigir estes defeitos, como a mecanização da produção.</p>